Conventionally, an achromatic lens which is configured by cementing two aspherical glass lenses is known (see Non-Patent Literature 1). The achromatic lens is designed to be suitable for a fluorescence microscope, a low S/N imaging application, or a biotechnology application, since the incident surface and the exit surface are respectively aspherical surfaces, for example, to favorably correct magnification chromatic aberration. However, it is very expensive because processing of the lens is difficult since it needs to process and to polish a glass lens into an aspheric surface having a complicated shape, and expensive glass having high refractive index and high dispersion characteristics is used.